Databricks launches UNIQUE constraints preview for Delta tables
Understand this story
Databricks has launched a public preview of UNIQUE constraints on Unity Catalog Delta tables, available for Databricks SQL and Databricks Runtime 18.2 and above. A table can declare multiple UNIQUE constraints, columns can be nullable, and foreign keys can also reference these constraints. Like Databricks primary key and foreign key constraints, UNIQUE constraints are informational only and are not enforced when data is written. Constraints are created as NORELY by default; after validating the data, change them to RELY so the query optimizer can use them to eliminate unnecessary joins and aggregations. This optimization is available only on compute with Photon enabled.
AI overview based on source reports · Updated 2 days ago
Coverage timeline
Follow the coverage to explore different perspectives.
- Databricks BlogDeclare and optimize with UNIQUE constraints on Databricks
Databricks introduces UNIQUE constraints in Public Preview for Unity Catalog Delta tables in Databricks SQL and Runtime 18.2+, allowing tables to record multiple uniqueness guarantees beyond a single non-nullable primary key, with nullable columns and foreign key references supported. Constraints are informational and unenforced by default; after validation, marking them RELY lets the query optimizer eliminate eligible joins and DISTINCT aggregations, with benchmarks showing 7.9x and 12.0x speedups on TPC-DS SF10000.
Activity for this story
- Current comparable activity
- 3
- Peak comparable activity
- 10Nov 4 06:00
- Change in the past 24 hours
- -49%
Trends compare the same fully observed participants, which may cover fewer participants than current activity. Move the pointer or tap the chart to inspect hourly activity; use the left and right arrow keys with a keyboard.